1. Field
One embodiment of the invention relates to a disk drive device including a head for data write/read to/from a disk medium, an electronic apparatus including the disk drive device, and a disk control method of controlling the disk drive device.
2. Description of the Related Art
In recent years, various portable electronic apparatuses, such as mobile phones and portable audio players, have been developed. In this type of portable electronic apparatuses, disk drive devices (hard disk drives (HDDs)) have recently been mounted more and more.
In the disk drive device, however, if the head strikes against a disk medium due to shock, etc. on the disk drive device, the surface of the disk medium would be damaged and normal data read from the disk medium would be disabled.
Under the circumstances, a disk drive device has been developed, which has a load/unload function for executing an unload operation of retreating the head to a retreat position, which is called “ramp”, and a load operation of loading the head from the retreat position onto the disk medium.
Jpn. Pat. Appln. KOKAI Publication No. 11-25625 discloses a disk drive device having a function for surely unloading the head at the time of power-off. In this disk drive device, the unload operation is automatically executed after the completion of execution of a process which corresponds to a command that is issued from the host immediately before power-off.
Jpn. Pat. Appln. KOKAI Publication No. 7-57416 discloses a disk drive device which includes a vibration sensor. In this disk drive device, if vibration is sensed by the vibration sensor, the unload operation is automatically executed.
As regards the disk drive device that is mounted on the portable electronic apparatus, however, there is a demand for reduction in size and weight. It is practically difficult to mount such a vibration sensor within the disk drive device. It is thus necessary to provide the disk drive device, which is mounted on the portable electronic apparatus, with a function of executing the unload operation in response to a command from the host.
In the ATA (AT Attachment)/ATAPI (ATA Packet Interface)-7 standard, an “Unload immediately” command is defined as a command for instructing execution of the unload operation. However, the “Unload immediately” command is a command which can be issued only after a process corresponding to an immediately preceding command is completed. Thus, the host cannot issue the “Unload immediately” command during the read/write process.
There is an idea that a dedicated interrupt signal for starting the unload operation is supplied from outside to the disk drive device. In this case, however, a read/write process, which is currently being executed, is forcibly finished, and the data transfer between the host and the disk drive device is stopped before it is completely executed. In this case, in order to completely execute the forcibly finished data transfer, the host has to re-issue a read/write command.